Wednesday, March 23, 2016

Yesterday I made probably the heaviest, and definitely the lightest frame bags I've ever made.
Both are from fabrics I don't use much, but from very familiar patterns.

The first is for a Surly ECR, and is made from #8 cotton duck fabric in olive green, with mil-spec velcro, also in olive green. I've never used cotton duck before, but it is very robust and good for backpacks. Plus it has a nice "old fashioned" look - if you're riding an ECR, you may as well have a frame bag to match. Weight is 1 lb 4 oz - a contender for the heaviest frame bag I've made. Features are dual compartment, and padding along the tubes.

Cotton duck is quite prone to fraying along the edges so every exposed edge of the fabric is covered with 1" grosgrain webbing. This not only prevents fraying but also increases seam strength and looks better. Since seams in cotton duck fabric are also more likely to pull through the fabric edge, I used a wider seam allowance and did 4 lines of stitching.

And here's the finished product!

I've made a few frame bags from 2.94 oz Cuben Hybrid fabric, but had not yet used one myself, and wanted to get a good feel for how they last. The fabric takes a layer of 1.43 oz cuben fiber laminate (dyneema fibers), and adds a 50 denier layer of polyester, which increases the strength and abrasion resistance, mitigates fraying, and can be dyed in more colors than the base cuben laminate. The fabric tensile strength is over 100 lb/in. Because the cuben fabric is a laminate (the x and y fibers are layed on top of each other, not woven through), it is easier for stitching to rip through. Also, a weak point is created at the stitching holes. To increase the seam strength, a lighter weight thread is used (so the stitch is properly balanced) and a smaller needle is used (to poke smaller holes in the fabric). But before stitching, I put on little adhesive patches of cuben in the corners (see picture below). This reinforces the fabric at the higher stress points. After the stitching is done, I seal the fabric edges with cuben seam tape, that is a 0.51 oz cuben laminate with adhesive backing. This strengthens the seam, protects the thread from abrasion, prevents fraying, and offers some extra water protection.

Here are the first two I've made, both of which have seen thousands of miles and are doing well. The purple one is for a small Salsa Fargo and only has a left map pocket (my favorite feature). The grey one is for a titanium road touring frame, and features a cut out for a water bottle, left map pocket, and a panel loader.

When I saw the fabric also available in high visibility orange, I knew it was time to make a cuben bag for my commuter bike. With the extra fabric I made a matching bag for the Jones Loop Bar.
Both bags also use parachute cord to connect to the bike - another experiment for me, though certainly not a first.

The frame bag weights under 5 oz - a candidate for lightest frame bag I've ever made (the purple cuben bag weighted 4.9 oz so is also a contender - but it was for a much smaller frame, but had a left map pocket). The frame bag it replaced weighted in at a stout 1 lb 2 oz making the new one a full 13 oz lighter!

One other sewing project of note, a customer requested a black bag with "red accents" for his Bruce Gordon Rock and Road touring frame to prepare for some upcoming all terrain adventures. Here's what I came up with.

Exploring the desert!

Who needs a sawzall... I need a workout!

Homemade wheel truing stand from the scrap pile at the antenna factory. It easily adjusts to any wheel diameter or hub width out there, and the axle dropouts are interchangeable so I can make different ones if need be to accommodate all the wacky modern axle standards. Now I just need an excuse to build a wheel.